The present invention relates to a valve arrangement for regulating the idling speed of internal combustion engines by controlling the quantity of air on the intake side of an intake manifold leading to the internal combustion engine, said arrangement having an electromechanical control member which has a solenoid by which a closure member can be moved via a control element against the force of a return spring.
Such valve arrangements serve to keep the idling speed of the engine as low as possible and at the same time also to regulate it in such a manner that, in the event of additional loads such as result, for instance, from auxiliary units, the idling speed does not drop down to an extent such the the engine stalls. For this purpose, the solenoid is acted on by a control current which is generated inter alia, as a function of the actual speed and which effects such a displacement of the closure member that the actual speed reaches a predetermined desired speed, substantially independently of disturbing variables.
When the solenoid is without current, the control member and, together with it, the closure member are moved by the return spring into either the fully open position or the fully closed position. This is the case if no current acts on the solenoid aside from the automotive operation.
However, this may also occur as a result of a defect by which the apply of current to the solenoid is interrupted.
In the traditional valve arrangements this has the result that the engine operates either with maximum idling speed or else with minimum idling speed, with the danger of the engine stalling.
One object of the invention is, therefore, to create a valve arrangement of the type described above which, by simple means, assures an idling speed which is as low as possible but at all times sufficiently high to prevent the stalling of the engine in the event of a failure of the solenoid.